Synthesis of a potential long term stem cell trafficking agent

Labeling with F-18 (t1/2=110min) and Cu-64(t1/2 =12.7h) has been most devoted for monitoring movement of cells over a time course. However, these radionuclides do not have sufficiently long half-life for long-term cell trafficking study. Therefore, here we report a simple method for cell labeling with I-131(t1/2=8d) and I-124(t1/2 =4.2d), which involves three step radiochemical synthesis of hexadecyl-4-[131/124I]-iodobenzoate[131/124I]. Treatment of 4-iodobenzoyl chloride with hexadecyl alcohol yielded hexadecyl-4-iodobenzoate, followed by nucleophilic aromatic substitution with hexabutyl tin. Hexadecyl-4-(tributylstannyI) benzoate was treated with H2O2, acetic acid, and [131/124I]NaI to give [131/124I]HIB. Octadec-9-enyl-4-iodobenzoate was prepared by esterfication of 4-iodobenzoyl chloride and oleyl alcohol, which was further converted to octadec-9-enyl-4-(tributylstannyI) benzoate. [131/124I]HIB was prepared in three steps efficiently. The radiolabeled [131/124I]HIB was obtained in good yield (56%) and high purity (93%) after HPLC purification. MicroPET imaging of [131/124I]HIB-labeled cells clearly showed persistent high accumulation in lungs up to 3d. Treatment of oleyl alcohol with 4-iodobenzoyl chloride gave octadec-9-enyl-4-iodobenzoate (47%), which was converted to octadec-9-enyl-4-(tributylstannyI)benzoate (61%), which can be radiolabeled with [131/124I] to give another cell trafficking agent, octadec-9-enyl-4-[131/124I]iodobenzoate([131/124IOIB). HIB is simple to prepare and label cells effectively. HIB-Iabeled kidney cells was trafficked by microPET up to 3 days. The synthesis of OIB is in progress to develop another long-term cell trafficking agent